Multiple nozzle gun type oil burner and control therefor



Oct. 19, 1948. J. A. LOGAN 2,451,964

MULTIPLE NOZZLE GUN TYPE OIL BURNER AND CONTROL THEREFOR Filed March a,1947 4 Sheets-Sheet 1 INVENTOR 'Joazw/ A. [OM/Y (Lia aw 1 A TTO EYS Oct.19, 1948. J. A. LOGAN MULTIPLE NOZZLE GUN TYPE OIL BURNER AND CONTROLTHEREFOR 4 Sheets-Sheet 2 Filed March 3, 1947 INVENTOR Joa'P/IA. lac-An!ATTO N EYS Filed Mafch s, 1947 4 Sheets-Sheet 3 t 6 w m U mm Z E R wm Wm H A n P a a 06L 1948- J. A. LOGAN 2,451,964

MULTIPLE NOZZLE GUN TYPE OIL BURNER AND CONTROL THEREFOR Filed March a,1947 4 Sheets-Sheet 4 1 I INVENTQR DJ BY 46 {2 ,40} 9 116 63 Q 69 ATTOREYS atcnte 9, 1948 MULTIPLE NOZZLE GUN TYPE OIL BURNER AND CONTROLTHEREFOR Joseph A. Logan, Hadley, Mass., asslgnor to Gilbert & BarkerManufacturing Company, West Springfield, Mass, a corporation ofMassachusetts Application March a, 1947, Serial No. 731,919 Claims. (Cl.158-28) This invention relates to improvements in oil burners of theso-called gun type for house heating systems.

From the manufacturers standpoint the success of his equipment in usedepends to a large extentupon the skill used in installing the oilburner in the home. The installing work is customarily done by menemployed by the distributors who buy from the manufacturers. Of coursethe. manufacturers supply literature and offer training to guide the menin the field to install oil burners to the home user's advantage. Yetthere are some features of the gun type burner which under to-daysroutine practice cause them to operate less efiiciently in the home thanthey can be made to operate under this invention. The object of theinvention is to provide a new and improved burner of the said type,feasible to be made at the factory, distributed for installation underto-days routine practice, and result in the user getting a burner in thehome to operate with a substantial increase of efilciency as compared toprior art burners. By efilciency is meant particularly the efficiency inthe burning of the oil with resulting economy in oil consumption. Insome installations the invention will avoid disagreeable noise in burneroperation as compared to prior art burners under the same conditions.

The structure and mode of operation of the invention is disclosed by wayof example and in detail. Considerable discussion is needed to show thereason for much of the detail.

For the house heating use, it is necessary to vary the firing rate ofthe burner over a certain range, say from a minimum of one gallon perhour to a maximum of two and three quarters gallons per hour. The firingrate is determined by the size of atomizing nozzle used. The size of thenozzle tobe used is determined bythe dealer who installs the burner. Themanufacturer desires to standardize on one size of burner which bymerely change of nozzle size will be adequate for any firin rate withinthe stated range. However, as the firing rate is varied of course therate of oil flow is varied and the rate of air fiow through the air tubeof the burner needs to be correspondingly varied. Using one air tube ofa given size, the change of rate of air flow will result in a change inthe velocity of the air supplied through the .tube to the oil atomizingnozzle. Over the desired range of firing rates, the variation in airvelocity is so great as to result in inefiicient mixing of air and oilat certain firing rates. For example, if the air tube is proportioned toprovide the proper velocity of air for eflicient mixing at a high firingrate, then, when air is passed through the same size tube at asubstantially less rate for low rate firing, the velocity of the airwill be lowered to such an extent that there will be a substantial lossin the efllciency of 2 the mixing of the air and oil. However, if theair tube is proportioned to provide the'proper velocity of air forefilcient mixing at a low firing rate, then, when air is passed throughthis same tube at a substantially greater rate for high rate firing, thevelocity of the air will be so high as to cause objectionably noisycombustion and possibly also to change the desired shape of the fiame.

This invention has for an object to provide in a burner of the describedtype for house heatin purposes, a plurality of air tubes of differentdiameters, arranged one within another, and valve means to enable theair for combustion to be supplied through one or more of these tubes,according to the oil firing rate selected for the burner.

The invention finds one preferred use in connection with a burner of thetype described, which is adapted to be fired at more than one rateaccording to the user's choice or as determined automatically by asuitable control, and the invention has for a further object to providemeans, whereby a change in the oil firing rate will automatically causea change in the number of air tubes used to supply the air forcombustion. In this way, for two rates of oil firing, two air supplytubes may be provided suitably proportioned so as to yield approximatelythe same velocity of air for high rate and low rate firing.

In the accompanying drawings:

Fig. 1 is a side elevational view of an oil burner embodying theinvention;

Fig. 2 is a. cross sectional view thereof taken on the line 2-2 of Fig.1;

Fig. 3 is a fragmentary top plan view, with parts broken away to showthe air inlet valve together with the manual means and the automaticmeans for moving it Fig. 4 is a sectional plan view taken on the line4-4 of Fig, 1 and showing the dual air tube structure and the valvecontrol therefor;

Figs. 5 and 6 are cross sectional views taken on the lines 5-! and 6-6,respectively, of Fig. 4;

Fig. 7 is a fragmentary sectional elevational view taken on the line 1-!of Fig. 2;

Fig. 8 is a sectional plan view taken on the line 8-8 of Fig. 6, showingthe firing rate selector valve;

Fig. 9 is a fragmentary sectional view of a detail relating to themounting of the air inlet valve;

Fig. 10 is a wiring diagram of the electrical elements and circuits ofthe burner;

Fig. 11 is a fragmentary sectional plan view showing a modification; and

Fig. 12 is a diagram illustrative of a modification in the control shownin Fig. 10.

Referring to these drawings, the invention will be disclosed in what isnow considered its best form, in which the spray producing means is anozzle of the oil pressure atomizing type. However, the ihve'ntion iscapable cf use with' other types of atomizing nozzles, as will be clearto those skilled in the art, and it is not intended to have theinvention limited to the use if the one specific type of atomizing meansshown in the drawings.

Referring first to Fig. 1. the frame of the burner includes a hollowcasting, which may be supported by a pedestall and which has a lowercylindrical part 2 and an upper part 3, forming a housing for a fanshown in part at 4 in Fig. 3. This fan delivers air at relatively lowpressure, say a few ounces, into the rear. end of the tubular passage 8(Figs. 1 and '7), which extends through part 2 and is closed at its rearend by a cover 8. On one face of the fan housing 3 (Fig. 3) is mountedan electric motor 1, which drives the fan 4 and an oil pump 8. The pumpis fixed centrally to the cross bar portion 3 of a U-shaped frame, thespaced legs I!) of which are fixed at their inner ends to the other faceof fan housing 3. A casing Ii encloses the frame 8, l3 and part of pump8 and has a plurality of air inlet openings l2. Air passes throughthese'openings into the hollow interior of casing ii and enters the fanhousing 3 through the inlet opening I3. An adiustable shutter I4controls this opening. The fan 4 is fixed directly to the shaft l5 ofmotor 1.

The pump shaft i8 is preferably. driven from the motor shaft by means ofa centrifugal clutch, the driving and driven elements of which arerespectively indicated at l1 and- I8. This clutch may be like thatdisclosed in my c'opending application Serial No. 672,106, filed May 24,1946, and its purpose is to delay the starting of the pump until the fanhas acquired considerable speed and to stop the pump before the fan. Thepump may, for example, be constructed as shown in the patem; to OsborneNo. 2,233,709, dated March 4, 1941, and include a cut-off valveandby-pass valve located in the casing i9. The pump is arranged to drawin oil through a suction pipe 20 (Fig. 1) and 'force it out through adelivery pipe 2| to the burner. The cut-off valve in the casing |8 willopen to allow flow from the pump to pipe 2| only after a predeterminedminimum pressure, say 85 pounds per square inch, has been established.The by-pass valve opens to allow oil to by-pass to the suction side ofthe pump, when. the pressure of the pumped oil reaches a predeterminedmaximum pressure, say 100 pounds per square inch.

Referring to Fig. 4, the tubular air passage 5, into the rear end ofwhich air is delivered by fan 4, communicates with two coaxiallyarranged tubes 22 and 23. The outer tube 22 has a flanged end 24 whichis fixed as indicated to the outlet end ofthe cylindrical member 2. Theinner tube 23 is supported from the outer tube by two circ'ular seriesof radial posts 25, each of which is riveted to both air tubes. Theouter and inner tubes 22 and 23 are provided on their outlet ends withair directing cones 28 and 21, respectively.

Within the inner tube 23 are arranged the oil atomizing means of theburner. In the particular example herein shown, such means consist oftwo nozzles 28 andv 29 (Figs. 2 and 4) of the oil pressure atomizingtype. These nozzles 28 and 29 have different capacities and may, forillustration, be

assumed to have the respective capacities of one and two gallons perhour. These nozzles 28 and 29 (Fig. 4) are mounted on the outer ends ofpipes 30 and 3| respectively, which are mounted in spaced parallelrelation and are secured at their inner ends to a casing 32, whichcontains a firing rate selector valve. The oil delivery pipe 2| from thepump 8 extends through a recess in cover 6 into passage 5 and isconnected to the valve casing 32 as shown.

The firing rate selector valve is best shown in Fig. 8. The oil supplypipe 2| communicates with one end or an inlet passage 33 formed incasing slidably mounted in cylinder 34. The stem 33 passes out of casing32 through a suitable packing 40 and a packing nut 4| and is providedwith a spring 42, which presses against a collar 43 on the stem andyieldingly holds it in the low firing rate position shown. In thisposition, the valve disc 38 blocks oi the high rate outlet 38 and thevalve disc 31 uncovers the low rate outlet 38 and enables it tocommunicate with inlet 33. If the valve is moved to its high firing rateposition, valve disc 31 will block off outlet 35 and valve disc 38 willopen outlet 38 and allow it to communicate with inlet 33. A longitudinalpassage 44, which extends from the outer face of one valve disc to theouter face of the other, enables oil to flow hack and forth from one endof the cylinder 34 to the other and thus permits ireedmovement of thevalve.

The valve 31, 38 may be moved to its high firing rate positionby meansof a lever pivotally mounted at 48 between ears 41 on the casing 32. Onearm of lever 45 has a lateral extension 43 (see also Fig. 7) whichunderlies the collar 43 and is operable, when actuated by means later tobe described, to raise the collar and thus the valve 31, 38. A lightspring 48 connects the lever 45 to one of the ears 4'! and yieldinglyholds extension 48 40 in contact with the collar 43.

The inner air tube 23 (Fig. 4) is proportioned to pass air at a rate andvelocity suitable for operation of the burner at the lower firing rate.When the burner is operated at the higher firing rate, air is suppliedat an increasedrate and then both air tubes 22 and 23 are used, the twoenabling air to pass at the increased rate without substantiallyincreasing the velocity. It is therefore necessary to provide means forclosing and opening the entrance to the annular passage 83 between theinner and outer air tubes. Such means, as shown, consists of an annularring 5|, to opposite faces of which are fixed stampings 52 of triangularshape in cross section. Th ring 5| has a diametrical part 83 (Figs. 5and 7) to which are fastened at their inner ends two studs 54, arrangedin spaced parallel relation (Fig. 7).

These studs are slidably mounted in bearings 88,

rovided on the valve casing 32, one above and one below the latter, asshown in Figs. 6 and 'l. The rear ends of the studs 54 are fixed to across bar 58. Springs 51, one encompassing each stud 54, are locatedbetween the part. 53 and the inner ends of bearings 55 and yieldinglyhold the air valve in the closed position shown. Centrally on the crossbar 56 (Figs. 4 and 8) are a pair of spaced ears 58 which receivebetween them the outer end of the long arm of a bell crank lever 59(Fig. 8) and to which such arm is pivotally connected by a pin 88. Bellcrank 58 is mounted between the described ears 41 ajacent lever 48 andis pivotally connected to such ears by the same pin 48. To the short armof bell crank lever 58 (Fig. 4) is connected a link 6| which extendsoutside the cylinder 2 and is connected to the lowthrough the casing IIand is fixed to one of the arms I8. Fixed to the fan housing 3, as bylegs 84 (Fig. 2), is a casing 85, which contains a solenoid. The core 88of this solenoid is connected to lever 82. When the solenoid isenergized by means to be described, lever 62 will be swungcounterclockwise, as viewed in Fig. 2, thus pulling link 8| outwardlyand swinging lever 59 clockwise, as viewed in Figs. 4 and 8. This willpull outwardly on the studs 54 compressing springs 51 and moving the airvalve 5|, 52 to its open position. In such position the parts 52 of thevalve serve as streamlining to guide th air around the air valve withoutcreating undue eddies.

The described lever 45 of the firing rate selector valve is actuated bythe bell crank 59 after the latter has opened the air valv to asubstantial extent. A projection 6'! (Fig. 8) on the bell crank engagesan abutment 88 on lever 45 and moves the latter to shift the firing rateselector valve to its high rate position. Thus, the annular air space 58between air tubes 22 and 23 is opened whenever the selector valve isshifted to cause operation of the burner at the high firing rate.

The ignition means for the burner may include the spark electrodes 59(Fig. 4) which are supported in proper position to ignite the spray fromeither nozzle 28 or 29. These electrodes are fixed one in each of twoinsulating tubes I8, which in turn are mounted for longitudinaladjustment in a support II, being suitably held in adjusted position asby the set screws I2. This support II also receives the low and highrate nozzle supply pipes 38 and SI respectively, which pipes aresuitably held to the support, as by the set screws 13 (Fig. 2) in amanner to enable longitudinal adjustment of the pipes and thus theatomizing nozzles which they carry. The support has three radiallyextending ins 14 (Fig. 2) the outer ends of which contact the innerperipheral wall of the inner tube 23- and centralize the support. Theselector valve casing 32 also has legs I5 (Fig. 6) which support it fromthe cylindrical member 2. The nozzles and spark electrodes may be heldin proper longitudinal position in the air tube 23 in any suitable way.For example, two rods 18 (Fig. '7) are secured at one end one to each oftwo ears TI on the valve casing 32 and the other ends I8 of the rods areout turned at right angles, as at I8, and received one in each of twodiametrically opposed notches formed in the rear end face of cylinder 2.The cover 8 holds the ends 18 tightly in their notches. The inner endsof these rods are threaded and secured to the casing by a pair nuts I5,in such a way as to enable longitudinal adjustment of the casing 32 andthus of the nozzles 28 and 29 and the electrodes 69. When the cover 8 isremoved, one may reach into the tube and disconnect the link 8i fromhell crank 59, after which the unit comprising firing rate selectorvalve, air valve, nozzles and ignition electrodes may be withdrawn fromthe rear end of cylinder 2 by pulling rearwardly on rods I5.

It has been stated that, when the firing rate selector valve is moved toits high rate position, air is supplied to the burner at an increasedrate. This is accomplished by opening the shutter I4 to increase theeifective area of the air inlet to fan- 4. This shutter is threaded on ascrew 88 (Fig. 3) and it is suitably held against rotation, as by a stud88', fixed on cross bar 9. The shutter has a central opening largeenough to clear the driven element I8 of the centrifugal clutch. The

screw 88 has an outer plain cylindrical portion,

which is mounted to slide axially as well as turn in a bearing 8I in thecross bar 8 and an inner plain cylindrical portion which is also mountedto slide axially as well as turn in a bearing 82 (Fig. 9) in the fanhousing 3. A spring 83 (Fig. 3) on the screw tends to hold it in theaxial position shown, in which a shoulder 84 on the screw abuts thecross bar 9. Threaded 'on this screw, near its outer end, is anadjustable abutment, such as a nut 85, and a lock nut 86 for holding theabutment in adjusted position. On the end wall of easing II (Figs. 1 and2), a lever 81 is pivoted at 88 and has one end forked to straddle screw88 in back of nut 85. The other end of lever 81 is connected by a link89 to the upper end of the described solenoid-actuated lever 82. Whenthe solenoid is energized, the lever 52 will be swung counterclockwise,as viewed in Fig. 2, thus pull ing on link 89 to cause lever 81 to swingclockwise, as viewed in Fig. 3, to engage nut and move screw 88 axiallyoutward and move the shutter energization of solenoid, depends on theposition of nut 85. The amount of movement of lever 81 is always thesame but the axial movement imparted to screw 88 can be varied byvarying the amount of lost motion between the lever and nut 85. The highrate position of the air shutter may be adjusted with precision byturning nut 85 on screw 88. The low rate position of the shutter may beadjusted with precision by turning the screw 88 which will move theshutter axially in or out as required.

The burner is arranged for intermittent operation under the control of aroom thermostat switch. The electrical connections are shownconventionally in Fig. 10. The room thermostat switch 98 is arranged toclose on a demand for heat from the burner and close a low voltagecircult, which is supplied from the secondary M of a transformer andwhich includes a relay coil 92, the thermostat switch 98, the secondary9I, and the wires 93, 94 and 95 that connect these elements in series.The primary 96 of this transformer is connected by wires 91 and 98 tosupply wires 99 and I88, respectively. The relay coil 92, whenenergized,operates a switch IN to close a circuit to the burner motor and to theignition means. The motor circuit may be traced as follows, from supplywire 99, wire I82, switch I8I,

' wires I83 and I88, motor I, and wire I85 to supply wire I88. Theignition electrodes 69 are connected by two wires I88 to the secondaryI81 of a suitable ignition transformer, the primary I88 of which isrespectively connected by wires I89 and M8 to the wires I84 and I85 andthus in parallel with the motor so as to be energized and deenergizedsimultaneously therewith.

The solenoid which serves to shift the lever 52 to adapt the burner foroperation at the high firing rate is shown at III. It may be controlledautomatically or manually as desired. As illustrative of the automaticcontrol, a thermostat switch I I2 is arranged in a circuit, whichincludes in series the solenoid III and relay switch I8I, this circuitbeing traced as follows, from supply wire 99, wire I82, switch I8I,wires I83 and H3, thermostat switch II2, wire H4, solenoid III, and wireH5 back to supply wire I88. The therrate of air flow to be increased andthe air valve 52 to be opened to enable both air tubes to conduct air tothe oilatomizing means. For manual operation. a push button switch Ill(Fig. 12) may be substituted tor the thermostat switch H2 and connectedto the wires 3 and III, respectively, so as to open and close thecircuit to the solenoid I I I in the same way that it was done by switchII2. This switch II may be located at any convenient point in one of theliving rooms of the house and it will then enable the burner to bechanged over for high rate firing without going into the cellar to reachthe burner. It is, however, obvious that the change over for high ratefiring may be'efiected by means of a hand lever (not shown) located atthe burner.

In operation, the burner is started up automatically by the roomthermostat 80 when there is a demand for heat. Oil will be supplied bypump 5 to nozzle 28 or 29 depending on whether the firing rate controlswitch H2 or 5, as the case may be, is open or closed. If this controlswitch is open, the burner will be operated at the low rate while if itis closed, the burner will operate at the high rate. Air will besupplied by fan 4 at a high or low rate according to whether theselector valve is set for high or low rate firing. If air is supplied atthe high rate, the air valve 5|, 52 will be opened by lever 59 when theselector valve and air shutter I4 are moved to high rate position. Thenthe two tubes 22 and 23 will be used to conduct air to the spray nozzle.If air is supplied at a low rate, the air valve 5|, 52 will be closed bylever 59 when the selector valve and air shutter are moved to low rateposition. Then, the inner tube 23 only will be used to conduct air tothe burner. The air tube arrangement aiiords two air conduits ofdiflerent cross sectional area, which can be proportioned so as to givethe proper velocity of air at the atomizing nozzle for high and for lowrate firing. As shown, one such conduit comprises the inner tube 22alone and is used for low rate firing and the other conduit comprisesboth tubes and they are used for high rate firing. The air supplied fromeach tube will mix with the spray emitted from the nozzle 28 or 29, asthe case may be, and the combustible mixture will be ignited by theelectrodes 69 in the usual way. The burner will continue in operationuntil the demand for heat is satisfied, when the burner will be stoppedby the opening of switch IOI, when the room thermostat switch 90 opens.On stopping of the burner, solenoid III will be deenergized and the airvalve 52, 53, the firing rate selector valve and air shutter It will beshifted back to low fire position. It is obvious, however, that thesevarious valves need not necessarily be shifted back to low fire positionwhen the burner stops. They might, for example, be operated manually andlatched in the high rate position in the same general way as is shown inFig. 11, hereinafter described.

The invention provides for an automatic change in the cross sectionalarea of the air supply conduit as the rate of oil supply is changed,

whereby the velocity of air at the nozzle may be maintained about thesame for both high and low rate firing. The arrangement enables oneburner to serve eiiiciently for all usual firing rates throughout therange normally used for house heating systems. the manufacturer wouldhave to supply burners with air tubes of different sizes, one for therelatively high firing ranges and another for the relatively low firingranges. I! a single air tube were used of the proper size to give thedesired air velocity for efilcient mixing of air and oil at high firingranges, the same tube, when supplied with air at a less rate for lowrate firing, would cause a decrease in air velocity so great as toresult in inefllcient mixing or the air and oil and poor combustion. Ita single tube were used properly proportioned to give the desired,airvelocity for efiicient mixing for low rate firing, then when the sametube is supplied with air at the greater rate needed for high ratefiring the velocity of the air would be so much increased as to resultin too noisy combustion and probably also in substantial change 01'shape of the flame. With the invention, the air velocity may bemaintained within a range to secure eflicient mixing for both low andhigh rate firing and to avoid noisy combustion.-

The invention is characterized in providing for the change in area ofthe air conduits as the oil firing rate is changed and, in its broaderaspects, is not limited to the one means herein disclosed for varyingthe oil firing rate. The invention is useful regardless of how thechange in oil firing rate is eflected.

The invention is also useful in all burners, wherein the change infiring rate has to be effected manually by changing the size of theatomizing nozzle used. This is indicated in Fig. 11, wherein a singleoil atomizing nozzle I I9 and the ignition electrodes 59 are mounted ina support I20 in the inner air tube 23. This nozzle is supplied with oilthrough pipe 2| under pressure regulated by the usual cut-ofl andby-pass valves but without any other valve control. mounted on studs 54as before and these studs are slidably mounted in a support I2 I in thesame way that they were formerly mounted in the valve casing 32. Each ofthe supports I20 and I2I has supporting legs as before and the twosupports are tied together by rods I22. Rods It are fixed at one end tothe support I2I and at the other end fit in recesses in the cylinder 2as heretofore. The support I2I pivotally supports the lever 59 whichactuates the cross bar 56 to which are fixed the studs 54 of the airvalve 5 I, 52. This lever may be manually operated fromoutside thecylinder 2 by pulling or pushing on a link I23. This link has adownturned end I which can be inserted in either of two holes I25 andI26 in an ear I21 on cylinder 2. When the end I24 is engaged in hole I25the air valve 5|, 52 will be closed for low rate firing and when suchend is engaged in hole I25 the air valve will be opened for high ratefiring. The burner manufacturer might supply two air tubes with eachburner, one tube to be used when nozzles of relatively low firing ratesare used and the other tube to be used when nozzles oi relatively highfiring rates are to be used. Such a-plan leaves the installation of thetube and that of the oil nozzle and ignition electrodes .to the dealerand the manufacturer has no assurance that the Installation of theseparts will be properly eflected. The invention enables both tubes andall the parts supported in them, except possibly for the nozzles Exceptfor the invention,

The air valve 5|, 52 is both of the tubes to be supplied with air by thefan.

From the foregoing disclosure it will now be clear that I have providedan improved oil burner for these advantages among others. When theworkman installs the improved burner for house heating, the householderwill get a burner better adapted for-that particular operation whichwill be eflicient in relation to his particular househeating needs. Theburner structure is better adapted for the installing workman tocondition it for emcient operation under the particular conditions ofthe house in which it is put for use. Whereas working with prior artburners different firing rates were determined by diiferent sizednozzles accompanied by different adjustments of air volume through thesame air tube, the improved burner takes into account the increase inefliciency of difierent sized tubes in relation to the operation ofdifferent sized nozzles. The structure is arranged at the factory forthe most convenient kind of installation work by men in the field withthe result that less skill is needed in'doing the installing work ofputting the mass produced burner into that kind of operation which is hihly efilcient for one particular house as com ared to diiferent housesand within a substantial range. This is one of the broader aspects ofthe invention which is pointed out in various aspects by the followingclaims.

I claim:

1. In an oil burner for house heating systems, a 2

motor, an air fan, an oil pump. a transmission for driving the fan andpump from said motor. two air tubes arranged one within the other with apassage between them, the inner tube being permanently connected toreceive air from said fan, valve means operable to connect or di connectsaid passage to or from the fan, oil atomizing means connected to be suplied from said pump at either a high or a low firing rate and located inthe inner tube in a position such that the air from the inner tube andthe air from the passage between the tubes will mix with the sprayemitted from the atomizing means, means for changing the firing rate ofthe atomizing means from a hgh to low rate and vice versa, and meansoperable with the rate changing means for actuating said valve means toopen and close the passage between said tubes when the atomizing meansis adapted for hi h and low rate firing res ectively.

2. In an oil burner for house heating systems. a motor, an air fan, anoil pump, a transmission for driving the fan and pump from the motor,two air tubes one within the other with a passage between them andconnectedto receive air from the fan, oil atomizing means connected tobe supplied by said pump and operable at either a high or a low rate.said means being located in the inner tube in a Position such that airfrom the inner tube and the air from the passage between the tubes willmix withthe spray emitted from said means, means operable to adapt saidatomizing means for high or low rate firing, and valve means operable topermit air from the fan to flow either through the inner tube or throughthe inner tube and the passage between the tubes to adapt the air supplyto the selected rate 01' oil supply.

3. In an oil burner for house heating systems. a motor, on air tan, anoil pump, a transmission for driving the fan and pump from the motor,two air tubes one within the other with a passage between them andconnected to receive air irom the fan, two oil conduits selectivelyconnectible to said pump and each arranged to end with an individualatomizing nozzle located in the inner tube in such position that airfrom the inner tube and the air from the passage between the tubes willmix with the spray emitted from either nozzle, valve means controllingthe selective connection of said oil conduits to the pump to vary thefiring rate of the burner, and a second valve means operativelyconnected to the first valve means and operable to permit air to flowthrough the inner tube or the inner tube and the passage between thetubes according to the selected firing rate.

4. In an oil burner for house heating systems, a motor, an air fan, anoil pump, a transmission for driving the fan and pump from said motor,twooil conduits selectively connectible to said pump and each arrangedto end with an individual atomizing nozzle, valve means to control theconnection of said 011 conduits to said pump to provide for a high and alow firing rate, and two air tubes arrangedone within the other with apassage between them, the inner tube being permanently open and bothconnected to receive air from said fan, said nozzles being located inthe inner air tube in such position that the air from the innertube andthe air from the passage between the tubes will mix with the sprayemitted irom'either nozzle, and a second valve means operativelyconnected to the first-named valve means and operable when thefirst-named valve means is moved into position for low rate and highrate firing to respectively close and open the passage between said airtubes, whereby one or both of said tubes is or are connected to the fanfor low and high rate firing respectively.

5. In an oil burner for house heating systems, a motor, an air fan, anoil pump, a. transmission for driving the fan and pump from the motor,two air tubes arranged one within the other with a passage between them,the inner tube being permanently connected to receive air from said fan,valve means operable to connect or disconnect the passage between thetubes to or from the fan, two oil conduits selectively connectible tosaid pump and each arranged to end with an atomizing nozzle located inthe inner air tube in such position that the air from the inner tube andair from the passage between the tubes will mix with the spray emittedfrom either nozzle, valve means for selectively connecting said oilconduits to said pump to provide for high and low rate firing, and meansconnecting the first and second valve means for opening and closing thefirst-named valve means when the second-named valve means isrespectively positioned for high and low rate I JosEPn a LOGAN.

REFERENCES crrEn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,932,269 Harrington, Oct. 24,1988 1,976,097 Sharp Oct. 9, 1984 2,067,441 Good Jan. 12, 1937 2,120,387Bargeboer June 14, 1988 2,203,553 Thoresen June 4, 1940 2,315,412Galumbeck H11. 80, 1948

